A gun carriage can normally swivel about a vertical azimuth axis and has a pair of cheeks flanking the cradle of the barrel and supporting same so it can pivot about a horizontal elevation or range axis that is perpendicular to the azimuth axis. To shoot accurately it is essential that the barrel not move relative to the carriage except angularly about the horizontal elevation axis.
Accordingly it has been suggested in German patent document No. 2,330,890 to provide the gun cradle with trunnions, that is cylindrical pins projecting coaxially oppositely along the horizontal elevation axis from the gun cradle. The cheeks of the carriage carry sleeve-type gudgeon journals that receive these trunnions. The difficulty of putting together such an assembly is considerable as very close tolerances must be observed throughout. In addition the tendency of the gun, particularly with the cannon tipped, to twist when fired and to rub when swiveled subjects the various elements to considerable stress. Thus wear is common, so that the barrel of an old cannon will cant limitedly on the elevation axis and thereby shoot inaccurately.
Other large-caliber guns have complex systems for bracing the barrel cradle relative to the carriage. Normally they employ slip joints and complex tightening assemblies. With this type of system it is possible to adjust out any wear. Nonetheless this adjustment procedure is extremely complex and must be carried out at each trunnion. Furthermore the manufacture of such a cannon is a complex and expensive procedure, as everything must be made to very close tolerances.